What are concrete hollow blocks?

Hollow Concrete Blocks

Hollow concrete blocks, concrete bricks, or concrete masonry are all names for what the industry calls Concrete Masonry Units, or CMU for short. Portland cement and aggregate (which might be sand and gravel or industrial waste) are the main components of a concrete block. Aerated concrete is used to create lightweight blocks.The hollow concrete blocks are exceptionally sturdy since they are made, hardened, and cured away from the construction site.

Uses of concrete hollow blocks

  1. Exterior and interior load-bearing walls.
  2. Curtain wall.
  3. Partition wall and panel walls.
  4. Backing from brick, stone and other facing
  5. Fireproofing over structural member
  6. Fire-safe walls around stairwells, elevators
  7. Boundry fences.
  8. Piers, column and retaining walls etc.

Advantages of concrete hollow blocks

  1. They're all the same size, and the two hollow centers within make them very lightweight.
  2. The air pockets in the cores make this a fantastic thermal insulator.
  3. In terms of acoustics and soundproofing, they perform well.
  4. They are affordable and cost effective as well.
  5. Its rough surface promotes strong adhesion between concrete blocks and mortar.
  6. Excellent resilience to the prevailing environmental conditions.
  7. Since it is so sturdy, the thickness of the inside walls may be decreased.
  8. These blocks may also be made from fly ash, making them a sustainable building material.
  9. They don't easily catch fire.

Disadvantages of concrete hollow blocks

  1. High maintainance cost
  2. Low bearing capacity as the average mass of the wall decoration materials is reduced, and the load bearing capacity is usually decreased.
  3. Very risky to hang huge things on walls.
  4. Hollow blocks are porous so high chances of water seepage.

Difference between Hollow blocks and Solid concrete blocks

Solid Vs Hollow Concrete Blocks
Sr.Solid BlocksHollow Blocks
1Solid in nature.Hollow in nature
2High in weight compare to hollow blocks.Less in weight compare to solid blocks.
3Less heat insulation.High heat insulation.
4Doen't provide facility to conceal conduits.Easy to conceal conduits.
5Lean mixes are used.Richer mix are used.
6No fine concrete is used.As high as 60% fine aggregate are used.

Concrete blocks—should they be filled?

When walls are built using concrete blocks, the structure of the blocks causes gaps inside the walls. If you want your concrete block wall to be as strong as possible, it's important to fill the gaps between the blocks with concrete or mortar.

Steel reinforcing bars, commonly known as rebar, may be used to further reinforce the concrete block wall, particularly in its resistance to cracking. By filling in the cores where the rebars have been inserted, you can be sure that the concrete blocks will bind properly with the rebars and produce a column-like structure throughout the length of the wall.

The following procedures for calculating the amount of the filling material are applicable to all types of concrete blocks, regardless of whether they are called concrete masonry units, concrete hollow blocks, or something else entirely. Lightweight concrete blocks, such as those made from cinders or ashes, will do as long as their forms are comparable.

How much quantity needed to fill a concrete block?

Depending on the size of the block, more or less concrete will need to be used to fill it. Concrete blocks are produced by casting concrete into molds to create two concrete planes or shells joined by a web or webbing of concrete.

We need to use concrete or mortar to fill the empty areas (cores or cells) between the webs. How much concrete is required to fill a wall may be calculated by measuring the volume of the cores in each block and multiplying that result by the number of blocks in the wall.

How to use the concrete block fill calculator?

  1. Select the thickness of the block you want to use for the wall. Block dimension will be auto populated. Change the dimension of the blocks, if you are using custom blocks. Following that, you'll be able to figure out how much core volume each individual block contains.
  2. Insert the length and height of the wall.
  3. We have included waste to calculate the overall filling material volume.

Sample block fill Calculation

Calculate the mortar required for the 3 meter long and 2.4 meter high wall using 8-inch thick standard 8" x 16" (20cm x 40cm) concrete hollow blocks.
The core volume of standard size 8-inch concrete block is approximately 8493 cm3 or 518.3 in3

Concrete Block needed =
Length of wall x Height of wall/Block Width x Block Height
Concrete Block needed =
3.0 m x 2.4 m/0.4 m x 0.2 m
= 90
As we know core volume per concrete block for 8-inch block is 8493 cm3,
Fill volume = core volume per concrete block × No. of concrete blocks needed
Fill volume = 0.008493 m3 × 90
Fill volume = 0.76437 m3
Assuming 5% wastage in filler material,
Final Fill Volume = 0.76437 x (1 + 5/100) = 0.8026 m3
Thus, from our calculation, we can say that, we need 0.8026 m3 concrete or mortar to fill void of concrete blocks.